Let's Make Robots!

My First Circuit

As you can see God spoke and there was LIGHT!

I'm trying to get the circuit thing down. I can code all day long but this electronic stuff is tricky...

Once I get it down pat I'll post some walkthoughs so other people like me who lack the electronics background can get stuff going easier. I won't post all my minor successes, but I did do a jig when the little light went on. My Picaxe stuff shipped today so I won't post more until I have motors and wheels moving ;)

The journey of a thousand robots begins with a single LED.


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My code looks like spagetti and my solder looks like chicken splatter,
who's gonna team up with me?


lolz.. lets make a straganoff ^_^ with the spargetti and the chicken, adding some mushrooms...

Brilliant !

You just gave me a great idea for a new project !  OSRC Open Source Robot Cookbook 

mmmm ... hungry already - I will continue to update it - feel free to add or change anything when you want..


hehe, go on, i'm with you

We should team up! I solder like a master and can build anything -metal or wood... I code like shit though... 

www.rocketbrandcustom.com baby!!

I ve got no idea how to use resistors or whatever there called to prevent the LED from burning out, just use a small curent and hope for the best. Unfortunatley that techinique doesnt work that often so i end up burning out alot of LED s. Hope one day to learn how to corectly use LEDs   

to limit the corrent that pass by the led, just do V = R I

I = V / R

i sugest 15mA, so:

15mA = V / R

you know the voltage that you aplly, 5V or 9V, or something.. so just need know the resistor to limit it, so:

 R = V / 15 mA

if V = 5V,  5/15 = 0,333(3) so use a 330 Ohm resistence

if V = 9V, 9/15 = 0,6 so use a 600 Ohm resistece.. if you can't find one use somthing close to it value.. does not to be the exactly value.

do the same to other voltages that you aplly.


Hope i helped you to understand it.


Tiago Rodrigues

Just remember to do the calculations in compatible units :-). If you use milli-amperes like in your example the result will be in kilo-ohms.

I always do calculations using volts, amperes and ohms (known as SI-units ... no milli-, kilo- or mega- etc). Then you will get

R = 5 V / 0.015 A = 333.33... ohms

TigPT, you seem to know a great deal about all this electronics stuff. Are you studying electronics or something like that?

- Jimmy


Aren't you supposed to use the supply voltage minus the  forward voltage drop in the equation? Like:

R = (Vs-Vf)/I.  The forward voltage dropdiffers from LED to LED, so consult your datasheet. I found a table on the net somewhere, that I use as a guideline:

Infrared 0,7 - 1,5 V
Red 1,8 V
Yellow 2 V
Green 2,2 V
Blue 3 V
White / Ultraviolet 3,3 - 3,6 V

So, to power a red LED with 20mA from a 5V source, the equation is: R=(5-1.8)/0.020=160ohm.

Which also means that you can't power a yellow LED with a 1.5V battery, because your supply voltage must be higher than the forward voltage drop.


think the zenner difrence from the collor leds are not so big, but anyway, its a round value if you make it for 15mA you have a gap to secure that you don't burn it.. anyway i will reaserch it